This invention relates in general to apparatus and methods for broadcasting particulate materials such as fertilizers over a prescribed area of a lawn, garden, or the like. More specifically, this invention relates to a fertilizer spreader in the form of an attachment assembly for use with a hand-held portable air blower to permit broadcasting of granular fertilizer or the like by use of the discharge air stream of the blower.
Hand-held portable air blowers in general are known in the art, and typically comprise a relatively lightweight housing in which is mounted an impeller for drawing air into the housing and for expelling that air through a discharge outlet at a relatively high flow rate. The impeller may be driven in any suitable manner, such as by use of an electric or gasoline motor, to provide the discharge air stream for use, for example, in blowing leaves or dirt from grass or pavement areas.
A variety of attachment kits and assemblies have been proposed for use with portable hand-held air blowers to increase the utility of such blowers by permitting the discharge air stream to be used for a variety of purposes. For example, attachment kits have been proposed for permitting selected operation of the blower in a vacuum mode, such as that shown and described in copending and commonly assigned U.S. Pat. No. 4,325,163. Alternatively, attachment kits have been proposed which permit use of the blower in cleaning leaves and other debris from rain gutters, such as that shown and described in copending and commonly assigned U.S. application Ser. No. 296,428.
Kits and devices have also been proposed for utilizing and relatively high velocity air stream of the blower to entrain and blow a particulate substance over a prescribed area. See, for example, U.S. Pat. No. 4,256,241. However, in the context of small portable air blowers of the type generally analogous to commercially available portable blowers for domestic lawn and garden use, these kits and devices have been intended primarily for use with relatively fine particulate substances of a dustlike composition such as many common pesticides. These prior art devices have not been well suited for entraining and blowing coarser particulate substances, such as granular fertilizers of the type and size typically used for domestic lawn and garden applications, primarily as a result of difficulties in obtaining uniform particle flow rates without clogging. Moreover, these devices have not provided satisfactory adjustment means to permit significant adjustment of particle flow rate or to allow use with particles having different sizes ranging from fine powders to coarser granules. Accordingly, fertilizers continue to be applied by use of conventional fertilizer spreaders which must be walked back and forth many times over a lawn or garden area to achieve the desired coverage.
The present invention provides an attachment assembly for use with a portable hand-held air blower, wherein the attachment assembly utilizes the blower discharge air stream to provide a source of pressurized air and a source of vacuum which cooperatively entrain fertilizer for flow into the blower discharge air stream at an adjustable and substantially uniform flow rate.